Corrosion inhibitor composition



United States Patent ABSTRACT OF THE DISCLOSURE A metal corrosion inhibitor for use with aqueous acids comprising specified amounts of an acetylenic alcohol or V sulfide, an amine or nitrogen base compound and a nonacetylenic alcohol.

The present invention relates to inhibition of corrosion and especially to new and useful compositions which may be employed in acid solutions to decrease or inhibit the corrosion of metal in contact with the acid solutions.

The present invention is particularly useful in the acidizing or treating of earth formations and wells traversed by a bore hole.

Many various types and compositions have been em ployed for the inhibition of corrosion of metal surfaces. Most have been employed with varying degrees of success. A particular failing of most prior art corrosion inhibiting compositions is that they cease to be effective after relatively short periods of time or break down under high temperature conditions, that is temperatures of 175 F. or higher.

It is therefore a primary object of the present invention to provide a new and improved composition for inhibiting the corrosion of metal surfaces in contact with acid solutions, which is effective for relatively long periods of time and at relatively high temperatures.

Another object of the present invention is to provide a corrosion inhibiting composition which is effective in acid solutions at both low and high temperatures.

Another object of the present invention is to provide a new and improved composition which may be added to acids, especially hydrochloric acid which will substantially inhibit the corrosion effect of the acids on metal surfaces, especially on steel and other ferrous metals, in contact with the acids.

Still another object of the present invention is to provide a new and improved corrosion inhibiting composition which may be employed in acidizing solutions used in well treating and which will effectively inhibit the corrosive action of the acid on underground well equipment.

Other objects and advantages of the present invention will become readily apparent from a reading of the description of the invention hereinafter.

It has been discovered that a synergistic blend of acetlyenic alcohol or alcohols, a nitrogen compound, and a compound having the formula ROH wherein R is an alkyl group or ketone, in particular amounts of each, provides a composition having superior corrosion inhibiting properties when added in small quantities to an acid solution.

In the preferred form of the invention, two or more acetylenic alcohols, each having an ethynyl hydrogen on the acetylenic group, are employed as the acetylenic alcohol component.

Some examples of acetylenic alcohols or compounds which may be employed in the present invention are: hexynol, dimethyl hexynol, dimethyl hexynediol, dimethyl hexanediol, dimethyl octynediol, methyl butynol, methyl pentynol, ethynyl cyclohexanol, 2-ethyl hexanol, phenyl butynol, and ditertiary acetylenic glycol.

Other acetylenic compounds which can be employed in accordance with the present invention are for example, butynediol, l-ethynylcyclohexanol, 3-methyl-1-nonyn-3-ol,

"ice

2-methyl-3-butyn-2-ol, also 1-propyn-3-ol, 1-butyn-3-ol, 1- pentyn-3-ol, l-heptyn-3-ol, 1-octyn-3-ol, 1-nonyn-3-ol, 1- decyn-3-ol, 1-(2,4,6-trimethyl-3-cyclohexenyl)3-propynel-ol, and in general acetylenic compounds having the general formula 4 wherein R is H, alkyl, phenyl, substituted phenyl or hydroxyalkyl radical, and the alpha Rs may be joined together to form a cyclohexyl ring.

Acetylenic sulfides having the general formula can also be employed in the present invention in lieu of the acetylenic alcohol. Examples of these are dipropargyl sulfide, bis l-methyl-2-propynyl) sulfide and his (2- ethynyl-2-propyl) sulfide.

The nitrogen or ammonia base compounds that can be employed in accordance with the present invention are those amines such as mono, di and trialkyl amines having from 2 to 6 carbon atoms in each alkyl moiety as Well as the 6 membered N-heterocyclic amines, for example alkyl pyridines and mixtures thereof. This includes such amines as ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, mono, di and tributylamine, mono, di and tripentylamine, mono, di and trihexylamine and isomers of these such as isopropylamine, tertiarybutylamine etc. This also includes alkyl pyridines having from 1 to 5 nuclear alkyl substituents per pyridine moiety, said alkyl substituents having from 1 to 12 car- :bon atoms and preferably those having an average of 6 carbon atoms per pyridine moiety, such as a mixture of high-boiling tertiary-nitrogen heterocyclic compounds such as HAP (High Alkyl Pyridines), Reilly l0-20 base and Alkyl Pyridines HB.

The non-acetylenic alcohols suitable for use in the present invention have the general formula ROH, wherein R is either an alkyl group or a ketone group. Some examples of these alcohols are diacetone alcohol, normal propanol, isopropanol, ethanol, methanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, and 1,5-pentanediol.

On a basis of a volume of the composition of the present invention is comprised as follows:

Percent Acetylenic compound 41-92 Nitrogen or ammonia base compound 3-9 Non-acetylenic alcohol 5-50 The non-acetylenic alcohol not only acts as a diluent and/ or solubilizer, but also contributes to the corrosion inhibiting effectiveness of the novel composition.

Another preferred composition of the present invention may be expressed by the formula D+E+F= 100% wherein:

D=Acetylenic compound4l%92% by volume E=Non-acetylenic alcohol-5%50% by volume =Nitrogen or ammonia base compound(.03-.09)

(D) (G) by volume wherein G=percent active ingredients or activity of the acetylenic compound.

On a basis of a volume of 100%, a more specific preferred composition, sometimes referred to herein as compound X or blend X, of the present invention is as follows:

Another preferred composition, sometimes referred to herein as compound Y or blend Y is as follows:

Compound Parts by Percent Percent volume by volume by Weight Propargyl alcohol 4. 54. 50 55. 7 Ethyl octynol 1. 20. 44 19.0 Alkyl Pyridines HB 0. 34 4. 63 5. 0 Diacetone alcohol 1. 5 20. 44 20. 3

In view of the cost of pure propargyl alcohol, it is economically preferable to use equal parts of crude propargyl alcohol and pure propargyl alcohol.

Another preferred composition, sometimes referred to herein as compound 2 or blend Z is as follows:

Compound Parts by Percent by volume volume Propargyl alcohol 3. 0 33. 94 Crude propargyl alcohol 1.0 11. 30 Ethyl octynol 1. 5 16. 97 Alkyl Pyridines HB. 0. 34 3. 85 Diacetone alcohol 3. 0 33. 94

A crude propargyl alcohol with about 75% active inu gredients, with the remainder being non-aqueous reaction products resulting from the production of propargyl alcohol is particularly preferred. Pure or 100% propargyl alcohol may be used, but it is more expensive than the crude propargyl alcohol.

Hexynol in lieu of ethyl octynol also gives superior results in the blend.

Alkyl Pyridines HB (assumed to be 100%) can be substituted with a less active percent of alkyl pyridines by increasing the amount to be added to the blend, while staying within the concentration range of from 3 to 9% by volume based on the active acetylenics present in the blend. Other suitable commercial nitrogen compounds are HAP (High Alkyl Pyridines) and Reilly 10-20 base.

A number of laboratory tests were conducted wherein the preferred blends of this invention, compounds X, Y and Z were tested at various temperatures, in various amounts and also compared with prior art corrosion inhibitors such as Compound A, prepared in accordance with the teachings of U.S. Patent No. 3,107,221 and consisting of 2 parts of acetylenic alcohols and 1 part Alkyl Pyridines HB, Rodine 213, and A-llO.

Procedure In these tests, the acid solutions were mixed by diluting B. HCl with water to the desired concentrations. The acid solutions were then titrated with a standard base solution to ascertain the exact acid concentration. The various acid solutions were prepared in advance in sufilcient quantities to complete an entire series of tests with the same batch of acid.

Corrosion coupons of various types of steel were ordered in sufiicient quantities to complete a series of tests on the same batch of coupons. The coupons were cleaned as follows: pickled in an uninhibited 10% HCl acid solution for 10 minutes, neutralized in a 10% solution of sodium bicarbonate, scrubbed by hand with a fine wire brush and a detergent containing a pumice, rinsed, dipped in acetone to remove the excess water and then dipped in alcohol and allowed to dry. They were then weighed to the nearest milligram and stored in a desiccator until time for use.

Tests were conducted at various temperatures.

The acid solution was poured into glass bottles in sufficient quantity to approximate the specific acid volume-to coupon surface area ratio that was desired. The quantity of acid used was dependent upon the surface area of the coupon to be tested. In most of the tests, a 25 cc./in. acid volume to coupon surface area ratio was used.

After the desired amount of acid was poured into the bottles, the inhibitor was added with a hypodermic syringe and the resulting soluiton was stirred with a glass rod. The inhibited acid solution was then placed in a water bath which had been set at a predetermined temperature and allowed to preheat for 20 minutes. After which time, the coupons were placed in the preheated inhibited acid solutions. The coupons were left in the acid solutions for the specified test time, then removed, neutralized, recleaned, rinsed, dipped in acetone then alcohol, allowed to dry, then reweighed.

The loss in weight in grams was multiplied times a calculated factor to convert the loss in weight to lbs./ft. /24 hrs. The factor was calculated as follows:

=F actor 1 dav l 454 XSurface Area of Coupon 111. X

For temperatures in excess of 200 F. tests were conducted in high temperature and pressure autoclaves that were designed and built by the Halliburton engineering department. The autoclaves are designed to withstand temperatunes up to 600 F. and pressures up to 10,000 p.s.i. They have rotating tables that hold the beakers containing the acid. This allows the acid to be agitated throughout the test. The autoclaves are unique in design in that they have an acid discharge valve over each beaker of acid. This allows a test to be terminated immediately rather than having to wait for the temperature to cool down sufiiciently so that the head can be opened. There are two temperature controls, one monitors the temperature of the oil in the autoclave and the other the temperature of the acid solution. The temperature of the acid solution is recorded on an electric motor driven chart throughout the time of the test.

The methods used in the high temperature corrosion tests were basically the same as the other tests. The only difference was in the acid volume-to-coupon surface area ratio which was approximately cc./in. (excess acid) and the mechanical operations of the autoclaves.

The results of these tests are set forth hereinbelow:

TABLE I.COMPARISON OF BLEND X, DOWELL A-llO AND RODINE 213 [Corrosion rates in lbs./tt. /24 hrs.]

Corrodent, 10% HCl Acid volume-surface area ratio, 25 cc./iu. Metal type, 416 stainless steel Test time Test Cone. in Corrosion rate (hrs.) temp. gals/1,000

1 Acid volume-surface area ratio, 55 ec./in.'-' (excess acid was used to assure that acid would not spend completely it inhibitor broke before end of test).

1 The .T-55 coupons used in these tests had a higher degree of corrosiveness than other J-55 coupon-s used for testing.

TABLE VIII.COMPARI S'ON OF BLENDS X, Y AND Z \VITH INDIVIDUAL COMPONENTS THEREOF Test temperature g F 200 Corrodent percent HCl Test time hours 6 Coupons stee1 N-80 Acid volume-surface area ratio cc./in. 25

Corrosion rates in lbs./ft. /24 hours Inhibitor Gone. in gals/1,000 Corrosion rate Alkyl Pyridines HB 6 0. 069 Crude propargyl alcohol 6 0. 032 Pure propargyl alcohol 6 0. 027 Ethyl octynol 6 0. 011 Diacetone alcoho 6 2. 907 Normal propanol- 6 2. 907

nd X 4 0. 005 Blend Y 4 0. 006 Blend Z 3 0. 008

The inhibitor or inhibitor composition of the present invention is operable when employed at temperatures as high as 300" F. in various acid concentrations. The corrosion which does occur is substantially uniform regardless of temperatures from 60 F. up to and in excess of 250 F. It provides long term protection at small concentrations of inhibitor. It is particularly effective on all types of steel and especially on that used in oil field grade pipe.

Applications in which the inhibitor of the present invention is particularly useful include oil-well acidizing solutions, metal pickling, cleaning and polishing baths, boiler-cleaning compositions and the like.

The corrosion inhibitor compositions of the present invention are particularly adapted for use in mineral acids, especially hydrochloric acid. It may also be employed in sulfuric, phosphoric and acetic acids and the like.

The inhibitor is preferably added to the acid in amounts by volume from about /2 gallon to gallons per 1000 gallons of acid. The amount of the inhibitor required will vary with the temperatures to be encountered and the strength or concentration of the acid used. A 15% hydrochloric acid is most common for oil well acidizing operations.

Broadly, the present invention relates to a new and improved corrosion inhibitor or composition for reducing the corrosive effect of acids on ferrous metals consisting essentially of an acetylenic alcohol or alcohols, a nitrogen or ammonia base compound and a non-acetylenic alcohol, in certain amounts of each.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof and suitable variation-s may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A metal corrosion inhibitor for use with aqueous acids which comprises, an acetylenic compound having a formula selected from the group consisting of:

RCEC-CIJOI-I and .M:

wherein in (A) and (B) each R represents a member selected from the group consisting of hydrogen, lower alkyl, phenyl, alkyl substituted phenyl and hydroxyalkyl, the alkyl substituted phenyl and hydroxyalkyl radicals having from 1 to 4 carbon atoms, inclusive, in the alkyl group and wherein in (C) each R represents an alkylene radical having from 1 to 4 carbon atoms; an amine selected from the group consisting of pyridine, lower alkyl pyridines, alkylamines having from 4 to 10 carbon atoms, inclusive, in each alkyl 'substituent, and hydroxy lower alkylamines; and a non-acetylenic alcohol having the formula ROH, wherein R represents a radical having from 1 to 8 carbon atoms selected from the group consisting of alkyl, ketone, hydroxyalkyl and mixtures thereof; wherein the acetylenic compound is present in an amount by volume of from about 41% to about 92%, the amine is present in an amount by volume of from about 3% to about 9% based on the amount of acetylenic alcohol, and the non-acetylenic alcohol is present in an amount by volume of from about 5% to about 2. A metal corrosion inhibitor for use with aqueous acids, which consists essentially of propargyl alcohol of about 4.0 parts by volume, ethyl octynol of about 1.5 parts by volume, diacetone alcohol of about 1.5 parts by volume, and alkyl pyridines having from 1 to 12 carbon atoms in the alkyl portion thereof of about 0.34 part by volume.

3. The composition of claim 2, wherein the propargyl alcohol comprises about 2 parts by volume pure propargyl alcohol and about 2 parts by volume crude propargyl alcohol.

4. The composition of claim 2, wherein the propargyl alcohol comprises by volume from about 1%99% pure propargyl alcohol and from about 99%-1% crude propargyl alcohol.

5. A metal corrosion inhibitor for use with aqueous acids, which comprises propargyl alcohol of about 4.0 parts by volume, ethyl octynol of about 1.5 parts by volume, diacetone alcohol of about 3.0 parts by volume, and alkyl pyridines having from 1 to 12 carbon atoms in the alkyl portion thereof of about 0.34 part by volume.

6. The composition of claim 5, wherein the propargyl alcohol comprises about 3 parts by volume pure propargyl alcohol and about 1 part by volume crude propargyl alcohol.

7. Thecomposition of claim 5, wherein the propargyl alcohol comprises by volume from about 1%-99% pure propargyl alcohol and from about 99%-1% crude propargyl alcohol.

8. A metal corrosion inhibitor for use with aqueous acids which consists essentially of by volume about 39.64% propargyl alcohol, about 14.87% ethyl octynol, about 3.37% alkyl pyridines having from 1 to 12 carbon atoms in the alkyl portion thereof, about 14.87% diacetone alcohol, and about 27.25% propanol.

9. The composition of claim 8, wherein the propargyl alcohol comprises about equal parts of pure propargyl alcohol and crude propargyl alcohol.

10. The composition of claim 8, wherein the propargyl alcohol comprises by volume about 1%-99% pure propargyl alcohol and from about 99%-1% crude propargyl.

11. A corrosion-inhibited mineral acid comprising an aqueous solution of mineral acid and from about 0.05% to about 2.0% by volume of a mixture consisting of from 4.1 to 9.2 parts by volume of an acetylenic compound having a formula selected from the group consisting of:

R-CEC-f-OH R-GEC OH and wherein in (A) and (B) each R represents a member selected from the group consisting of hydrogen, lower alkyl, phenyl, alkyl substituted phenyl and hydroxyalkyl, the alkyl substituted phenyl and hydroxyalkyl radicals having from 1 to 4 carbon atoms, inclusive, in the alkyl group and wherein in (C) each R represents an alkylene radical having from 1 to 4 carbon atoms; from 0.3 to 0.9

parts by Volume of an amine compound selected from the group consisting of pyridine, lower alkyl pyridines, alkylamines having from 4 to 10 carbon atoms, inclusive, in each alkyl substitutent; and, from 0.5 to 5.0 parts by volume of a non-acetylenic alcohol having the formula ROH, wherein R represents a radical having from 1 to 8 carbon atoms selected from the group consisting of alkyl, ketone, hydroxyalkyl and mixtures thereof.

References Cited HERBERT B. GUYNN, Primary Examiner. 

